Cromemco ZPU Rev E 1976 pdf

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CROMEMCO ZPU

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CROMEMCO Z-80 CPU

Assembly Instructions

If you purchased your Cromemco Z-80 CPU as a kit, you will find that the assembly is easy and can be completed in about one evening. All components are inserted from the component side of the pc board (the side with the white printed legend) and soldered to the opposite side. Be sure to use high-qual-ity rosin core solder for the assembly and a fine-tipped low wattage soldering iron.

To ease assembly, the printed legend on the pc board shows the exact position and orientation of every component. The following step-by-step instructions are presented to guide your assembly:

( ) Solder in position the ~-watt 5% carbon film resistors:

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Z-80 CPU Assembly Instructions. (cont.)

( ) Solder in position sockets for all ICs (except the vOltage regulators ICI and IC2). Also install IC sockets for the two dual- in -1 ine res istor packag;es:, RNI and RN2, and install an IC socket at position Jl to accept a connection from the front panel.

( ) Install the 26 capacitors as shown on the pc board. WHEN INSTALLING THE 10 mfd TANTALUM CAPACITORS MAKE CERTAIN THAT THE + END OF THE CAPACITOR IS ORIENTED AS SHOWN ON THE PC BOARD.

( ) Solder in position the single-in-line resistor network (RN3) noting that the indentation marking pin 1 of the package should be oriented toward the top of the pc board.

( ) Solder in position the single-in-line resistor network RN4 noting that the indentation marking pin 1 of the package should be oriented toward the left of the pc board.

( ) Install Ql, a 2N3904 transistor, with the flat side fac-ing the top of the pc board.

( ) Next" install the heatsink and voltage regulator ICs (ICI and IC2) in the upper left-hand corner df the pc board. Take care that none of the leads of the regulators touches the side of the opening in the heat sink.

( ) Solder in position the speed-select control switch just to the right of the heatsink.

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Z-80 CPU Assembly Instructions. (cont.).

of the control switch. To mechanically secure the crystal you may solder a short piece of #24 wire to the hole on one side of the crystal, pull the wire tightly over the top of the crystal through the hole on the opposite side and solder it in place.

( ) Solder in position the four-,position mini-dip jump address select switch on the right side of the pc board. The arrow showing the closed or "on" position of the switch should point to the right.

( ) Install all ICs and the dual-in-line resistor networks in their sockets. For the Z-80 (ICS) pin #1. oriented towards the lower left corner of the board. Pin #1 of all other ICs is oriented towards the upper left corner of the board. TAKE SPECIAL CARE TO SEE THAT EACH IC IS INSERTED IN THE PROPER SOCKET, THAT EACH Ie IS ORIENTED PROPERLY, AND THAT

EVERY PIN OF EVERY IC HAS PROPERLY ENTERED THE SOCKET.

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OPERATING INSTRUCTIONS

The Cromemco ZPU is an S-lOO bus CPU (Central Processing Unit) using the powerful Z-80 microprocessor. This CPU is used in Cromemco computers and is also a plug-in replacement for the CPU card used in the Imsai 8080 and Altair 8800 computers.

The Cromemco ZPU has an exclusive set of features to increase the power of your total computing system. Most important, the ZPU was designed from the outset for reliable operation at 4MHz clock rate - twice the speed of most microcomputer

systems. The ZPU also offers an on board wait state generator, optional independent selection of MI wait states, power on

jump capability, address mirroring circuitry, refresh address mirroring circuitry, and other features all discussed in this section.

Power-on jump. Power-on jump may be used if you wish to have your computer jump to any 4K boundary in memory fqllowing .reset. The address of the 4K boundary is selected by the four position slide-switch on the right side of the ZPU card. This option is enabled by a foil trace connecting the two pins marked "jump enable" on the ZPU card. It can be disabled by cutting this trace.

When the jump enable pins are connected together, a hardware jump instruction is automatically executed following a reset

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Operating Instructions (cont.)

will appear on the data lights indicating the low order 8 bits of the jump address. Now press the examine next switch again; the high order 8 bits of the jump address will now appear on the data lights. The low order four bits will indicate zeros. The high order four bits will correspond to the setting of the four position jump address switch.

The power-on jump circuitry allows the ZPU to be used in 5-100 bus systems without any front-panel controls whatsoever (e.g. in the Cromemco 2-2 computer). When power is turned on program

execution automatically begins at the location in memory selected by the four-position slide switch.

If your computer has both "reset" and Hexamine" front panel controls note that the function of each of these switches is affected when the automatic jump feature is enabled. Following

re~et the first instructi6n executed is not the instruction at

. 10cati6n zero in 'memory, but rather is the instruction generated 'on the ZPU card causing a jump to the location specified by the

jump'address switch. After

a

reset (assuming that the computer

"is stopped) the examine switch must be activated twice in order, to examine a memory location: once to clear the'automatic jump and a second time to perform the actual examine operation.

The automatic jump feature is a very useful one. In Cromemco computers, for example, the'Z-80 monitor is designed to reside

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Address mirror selection. One characteristic of the 8080 micro-processor is that the 8 bits specifying the address of an input or output port are repeated in both the low order 8 bits and the high order 8 bits of the address bus. Although this characteris-tic is not inherent to the newer Z-80 microprocessor, our ZPU

card is designed to mimic this behavior through the address mirror circuitry. This is to assure compatability of our ZPU card when up-dating older 8080 systems.

The address mirror circuitry is automatically enabled by the short piece of pc board foil running between the "AM" pad and the "ON" pad on the ZPU card between IC7 and IC8 on the card.

In the event you wish to disable this circuitry this short piece of foil should be severed, and a small jumper wire should be installed connecting the "AM"·pad to the "OFF" p(id.

Refresh enable. When using certain· types of dynamic memory boards that require that the refresh address provided by the Z-80 is mirrored in the higher order address bits, a jumper wire should be installed between the two pads labeled "RF8H ENAB". Normally no jumper wire is installed here.

4 MHz Operation. To switch from 2 MHz operation to 4 MHz opera-ation simply flick the speed select switch on the ZPU from the 2 MHz to the 4 MHz position. Notice that the line previously labeled the "stack" line oQ. the 8-100 computer bus is now used as the 4 MHz indicator line. If you use the ZPU in an Altair or IM8AI computer your stack light will be on for 4 MHz opera-tion and off for 2 MHz operaopera-tion. (This indicator light is

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Wait state selection. The ZPU feat~res an on board wait state generator to insert optional wait states between the T2 and T3 cycles of each machine cycle. This is particularly useful if you desire 4 MHz processor speed using memory boards designed

for slower

Z

MHz operation.

If your memory boards have a true access time of 500 nanoseconds or faster they may be used without wait states at Z MHz opera-tion. If your memory boards have a true access time of 250 nanoseconds or faster they may be used without wait states at 4 MHz operation.

In each of these cases foil traces on the pc board select zero wait states as follows: one trace from pin Ml to pin 0; one

trace from pin W to pin O. This is shown in the figure .below:

Ml

o

1

2 .0

3 0

o

o I

w

PC board traces select zero wait states.

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Installation in Altair or Imsai Computers

If you are using an IMSAI computer the cable from the front panel may be plugged directly into socket Jl on the ZPU card. For the Altair computer a DIP plug must be installed in place of the Molex connector on the front panel cord; in doing this be aware that the data lines are not arranged sequentially on the Altair connector but are sequential on the ZPU card as shown:

Jl

I I I I I 1 I 1

D7 D6 DS D4 D3 D2 Dl DO Arrangement of data

lines on Jl of ZPU

o 0 0 0 0 0 0 0

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ZPU PARTS LIST

CAPACITORS

ClIO uF Tantalum C2 .001 disc ceramic C3 .005 disc ceramic C4 .005 disc ceramic CS 0.1 disc ceramic C6 10 uF Tantalum

C7 150 pF disc ceramic C8 56 pF disc ceramic C9 10 uF Tantalum C10 10 uF Tantalum

Cll - C24 0.1 disc ceramic C25 150 pF disc ceramic C26 .05 disc ceramic

INTEGRATED CIRCUITS

. ICl, IC2 LM340T-5 (or 7805) IC3 74164

IC4 74157

lCS Z-80 (4MHz Version) IC6 74LS04

IC7 74LSlO IC8 7400 lC9 7474 ICIO 7404 ICII 74367 lC12 74367 IC13 74367 IC14 74367 IC15 74LS04 IC16 74157 IC17 74LS10 lC18 7400 lC19 7474 Ie20 74LS04 IC21 7474 IC22 7408 IC23 74367 IC24 74367 IC2S 74367 IC26 74367 IC27 74367 Ie28 74S133 IC29 74164 IC30 7474 IC31 74LS04 IC32 7400 IC33 74LS04 IC34 74LSOO IC3S 74LS02 IC36-41 74367

RESISTORS

Rl 1K

R2 1K

R3 180

R4 180

RS 270

R6 270

R7 10K

R8 390

R9 330

RIO 330 Rl1 1K R12 100 R13 180 R14 100 R15 330 R16 330 R17 560

RN1 4.7K RN2 1K RN3 lK RN4 1K

OTHER

resistor network resistor network resistor network resistor network

Ql 2N3904 transistor Xl 8 MHz crystal

SWI Speed select switch SW2 Jump address switch Heatsink

(DIP) (DIP) (SIP) (SIP)

6-32 screws and nuts (4 each) 24 gauge wire

40 pin lC socket (1) 14 pin IC sockets (22) 16 pin Ie sockets (21) Printed circuit board

SOFTWARE

Cromemco Z-80 Monitor (paper tape)

DOCUMENTATION

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WARRANTY

Your factory-built ZPU is warranted against defects

in materials and workmanship for a period of 90 days

from the date of delivery. We will repair or

re-place products that prove to be defective during the warranty period provided that they are returned to

Cromemco. No other warranty is expressed or implied.

We are not liable for consequential damages.

Should you factory-built ZPU fail after the warranty

period, i t will be repaired provided that i t is

re-turned to Cromemco, for a fixed service fee. We

reserve the right to refuse to repair any product

that in our opinion has been subject to abnormal

electrical or mechanical abuse. The service fee is

currently $35 and is subject to change.

Your assembled ZPU kit will be repaired, provided

that i t is returned to Cromemco, for a fixed service

fee. We reserve the right to refuse repair of any

kit that in our opinion has not been asseIDb1ed in a

workmanlike manner or has been subject to abnormal

electrical or mechanical abuse. Payment of the

service fee must accompany the returned merchandise. The service fee is currently $35 and is subject to

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